Add a safeguard for ExPlat assignment requests to make sure a user either has an anon_id defined and not empty

packages/js/explat/src/assignment.ts

@@ -52,6 +52,12 @@ export const fetchExperimentAssignment = async ( {
 			`Tracking is disabled, can't fetch experimentAssignment`
 		);
 	}
+	if ( ! anonId ) {
+		throw new Error(
+			`Can't fetch experiment assignment without an anonId or auth, please initialize anonId first or use fetchExperimentAssignmentWithAuth instead.`
+		);
+	}
+
 	return await window.fetch(
 		`https://public-api.wordpress.com/wpcom/v2/experiments/${ EXPLAT_VERSION }/assignments/woocommerce?${ getRequestQueryString(
 			{

packages/js/explat/src/test/assignment-test.js

@@ -41,6 +41,14 @@ describe( 'fetchExperimentAssignment', () => {
 			'https://public-api.wordpress.com/wpcom/v2/experiments/0.1.0/assignments/woocommerce?anon_id=abc&test=test'
 		);
 	} );
+
+	it( 'should throw error when anonId is empty', async () => {
+		const fetchPromise = fetchExperimentAssignment( {
+			experimentId: '123',
+			anonId: null,
+		} );
+		await expect( fetchPromise ).rejects.toThrowError();
+	} );
 } );
 
 describe( 'fetchExperimentAssignmentWithAuth', () => {

plugins/woocommerce/includes/react-admin/class-experimental-abtest.php

@@ -122,6 +122,10 @@ final class Experimental_Abtest {
 
 		// Request as anonymous user.
 		if ( ! isset( $response ) ) {
+			if ( ! isset( $args['anon_id'] ) || empty( $args['anon_id'] ) ) {
+				return new \WP_Error( 'invalid_anon_id', 'anon_id must be an none empty string.' );
+			}
+
 			$url      = add_query_arg(
 				$args,
 				sprintf(

plugins/woocommerce/tests/legacy/unit-tests/woocommerce-admin/includes/class-experimental-abtest-test.php

@@ -61,9 +61,9 @@ class Experimental_Abtest_Test extends WC_Unit_Test_Case {
 		);
 	}
 
-		/**
-		 * Tests retrieve the test variation when consent is false
-		 */
+	/**
+	 * Tests retrieve the test variation when consent is false
+	 */
 	public function test_get_variation() {
 		delete_transient( 'abtest_variation_control' );
 		add_filter(
@@ -90,4 +90,17 @@ class Experimental_Abtest_Test extends WC_Unit_Test_Case {
 			'treatment'
 		);
 	}
+
+
+	/**
+	 * Tests return request_assignment wp error when anon_id is empty
+	 */
+	public function test_request_assignment_returns_wp_error_when_anon_id_is_empty() {
+		$exp = new Experimental_Abtest( '', 'platform', true );
+
+		$this->assertEquals(
+			is_wp_error( $exp->request_assignment( 'test_experiment_name' ) ),
+			true
+		);
+	}
 }